Smoking preparation containing laminar alumina and smoking unit containing same



United States Patent of Maryland No Drawing. Filed Feb. 25, 1960, Ser. No. 10,889 4 Claims. (Cl. 13117) The present invention relates to smoking mixtures containing tobacco mixed with a finely divided solid material and to smoking units, especially cigarettes, containing the same. The invention has for its principal object the provision of a smoking mixture of such a character that the tobacco therein burns with an appreciably reduced tar content and the tobacco smoke is characterized by a smooth, pleasant aroma and taste.

The desirability of reducing the tar content in the mainstream of tobacco smoke, that the smoke passing through the mouth end of a smoking unit, is well recognized. Tar from tobacco smoke is believed to be injurious to health and produces discoloration of the teeth. Most attempts in the past to reduce the tar content of smoke have centered on the use of a porous filtering means integral with and forming an end of the smoking unit.

I have discovered that when a very small amount of a lightweight laminar form of alumina, hereafter described, is mixed directly with smoking tobacco, the quantity of tar normally produced by the tobacco and passing into the mainstream smoke is significantly reduced.

Briefly stated, tobacco compositions of the present invention contain tobacco mixed with a small quantity of a finely divided lightweight laminar alumina supplied under the trade name Micria AL, a form of X alumina. Micria AL is chemically a substantially pure form of alumina which contains a small but finite water of hydration. A typical sample analyzes about: 95% A1 0 1% loss on drying (220 F. under vacuum), 3% loss on ignition (1832 F., 1 hour). Some of the physical properties "bf Micria AL are as follows:

Bulk density (ASTM) 2 lbs/cu. ft.

Crystal form Mostly X, A1 0 plus a small amount of Particle shape Flakes and shells. Particle size (microns) Width 0.15-30, avg. 3.5. Thickness 0.0l-0.05, avg, 0.02. Surface area 28 sq. m./ g. Conversion to alpha form 2300 F.

The X-ray diffraction pattern of Micria Al is somewhat diffuse, indicating a rather .poorly ordered crystalline state.

The more significant d values and corresponding line intensities for Micria AL are given in Table A, wherein values were obtained from the X-ray powder diffraction pattern, using the Ka doublet of copper, an X-ray diffractometer using a scintillation counter and a strip chart pen recorder. The relative intensity of the peaks and the interplanar spacings (d values) were calculated from the peak heights recorded on the chart in the conventional manner.

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TABLE A d Values 0 Relative Intensity of Reflections in Angstrom Units, Micria AL 5 d spacing, A. Relative intensity, 100 I/I 1 All peaks are broad.

When a smoking preparation containing a mixture of tobacco with this particular form of alumina is smoked, the quantity of tar present in the smoke is appreciably less than that produced when the same weight of the tobacco is smoked in the absence of this alumina additive. The alumina is innoxi'ous and has no harmful effects on the smoker even if it passes into the smokers mouth.

It has been found that aluminas difier profoundly in their effect on the tar content of smoking tobacco when they are mixed with the tobacco. Some forms of alumina and alumina hydrates, such as bauxite (a naturally occurring alumina trihydrate) have been found to increase the tar content. Other forms have little efiect on the tar content. It has been found, too, that some forms of alumina are eminently effective when they are mixed with tobacco in amount of the order of 10 percent of the tobacco weight but lose much of their effectiveness when they are mixed with the tobacco in considerably smaller quantity, such as 5 percent of the tobacco weight. The alumina I employ is eminently effective at the 3-5 percent level.

Prior to my present discovery, it appeared that optimum tar reduction could be obtained with a very fine high surface area alumina, e.g., an alumina having a BET. surface area of the order of 150 square meters per gram. As mentioned, the surface area of the alumina I employ in accordance with the instant invention is only about 28 square meters per gram. Also, I have conducted smoking tests which indicate that particle size and crystalline habit of an alumina are not the sole criteria in determining capacity to reduce tobacco tars. By way of example, a dense form of X-Al O supplied under the trade name Mircia AD and having a particle size similar to that of Micria AL and a surface area of 34 square meters per gram, has been found to be markedly inferior in reducing tobacco tars, as compared with the lightweight Micria AL. The dense form of X-Al O contains irregular, 55 spongy particles having a bulk density of 8.8 lbs. per cubic foot; its chemical analysis and average particle size are essentially the same as that of Micria AL.

The tobacco I employ is conventional leaf tobacco of the type used in cigarettes, pipes or cigar filling. It is reasonable to expect that reconstituted tobacco or mixtures of tobacco leaf and reconstituted tobacco may be used.

In putting my invention into practice, the laminar alurnina is mixed with shreds of tobacco in amount of about 0.75 to 5 percent, and more preferably about 3 to 5 percent, based on the weight of the tobacco. The optimumquantity of alumina to be incorporated with the tobacco will vary with tobacco type and the extent to which the tobacco is packed. Preferably the mixture of tobacco and laminar alumina powder is as uniform as possible to assure uniformity of pressure drop throughout the tobacco during smoking.

Any method of uniformly dispersing the alumina on the tobacco particles may be used. The additive may be applied by dusting the dry material on the tobacco by spraying a dispersion of the additive in a liquid or gaseous carrier or by other means which will readily suggest themselves to those skilled in the art. The alumina is very fine, and will usually adhere well to the tobacco without an adhesive. However, if desired, an adhesive, inorganic or organic, may be employed to secure the alumina particles to the tobacco.

Preferably, the tobacco to which the solid alumina is applied is in a form suitable for direct use in the cigarette or other smoking article for which it is intended, namely tobacco which has been aged, shredded, humected and treated with flavoring agents and such other tobacco treating materials as may be desired.

A filter tip integral with the column of the mixture of alumina and tobacco shreds may, if desired, form the mouth end of a cigarette of my invention. The filter tip may contain other microporous materials as are used in a filter tip for a cigarette. The filter tip in a cigarette of the present invention will serve a plurality of important functions. It will supplement the tar reduction realized through the use of the alumina and it will minimize the possibility of alumina particles passing into the smokers mouth.

The following examples are given to illustrate more fully the advantage of incorporating laminar alumina in smoking tobacco.

Tests were carried out to demonstrate that the total quantity of tar passing into the mainstream of the smoke from a given weight of cigarette tobacco is reduced to a remarkable extent when a small quantity of Micria AL is uniformly mixed with the tobacco. For the purpose of comparison, tests were conducted to show the efieot of Micria AD on the tar content of the same weight of the tobacco.

A blend of Turkish and domestic cigarette tobacco supplied under the trade name Bugler was used in all smoking preparations.

Control cigarettes were prepared by packing about 0.90 gram of the tobacco in a cigarette wrapper weighing about 60 milligrams. Cigarettes of the present invention were prepared by dry mixing 100 parts by Weight of tobacco with 5 parts by weight of Micria AL until an apparently uniform mixture was obtained and then packing about 0.95 gram of this mixture (containing about 0.90 gram tobacco) in a cigarette wrapper.

In making up experimental cigarettes containing Micria AD, parts of this alumina-were uniformly dry mixed with 100 parts of tobacco and individual cigarettes containing about 0.99 gram of the mixture were produced. This quantity of Micria AD was selected to be twice that employed in cigarettes of the present invention in order to emphasize the superiority'of the Micria AL as a tar reducing agent. All cigarettes were conditioned at 24 C. and 58 percent R.H. before smoking.

The cigarettes were mechanically smoked by the method described in detail in Industrial & Engineering Chemistry, vol. 28, No. 7, in .an article entitled Nature of Cigarette SmokeTechnic of Experimental Smoking, I. A. Bradford et al., pp. 836-839 (1936).

Cigarettes were smoked individually employing a constant puff of about 2 seconds duration once each minute and with sufiicient pufis to leave a butt of about 22 mm. The smoke from five replicas of each tobacco composition was collected in a glass-wool trap packed to give about 40 cm. water pressure drop at the flow rate of 1050 cc. of air per minute. The trap was shown to collect at least percent of the nonvolatile components of the smoke. The trap was evacuated for 20 minutes and weighed. The weight increase divided by 5 was reported'as the milligrams of tar per cigarette.

The results reported below represent the average of three determinations, each determination representing the result of smoking five replicas.

THE EFFECT OF MIXING VARIOUS TYPES OF XA12O ON THE TOTAL TAR CONTENT OF CIGARETTE SMOKE 1 Each cigarette containing 0.90 gram tobacco. 2 Based on tobacco weight.

The results reported in the accompanying table show that the lightweight, laminar X-alumina, Micria AL, effected a remarkable reduction in the tar content of the cigarette when only 5 percent of this material was mixed with the tobacco. The data shows also that the dense form of -alumina, Micria AD, was only about half as effective as the Micria ALin spite of the fact that the Micria AD was employed in double the quantity of the Micria AL.

I claim:

1. A smoking preparation comprising smoking tobacco mixed with a small amount of the laminar form of X- alumina, said alumina being further characterized by having an ASTM bulk density of about 2 lbs./cu. ft.

2. A smoking preparation comprising an apparently uniform mixture of shreds of cigarettetobacco and a small amount of the laminar form of X-alumina, said alumina being further characterized, by having an ASTM bulk density of about 2 lbs./cu. ft.

3. A cigarette comprising a paper wrapper enveloping the smoking mixture of claim 2.

4. A cigarette comprising a paper wrapper enveloping the smoking mixture of claim 2 and having an integral filter tip forming one end thereof.

References (Iited in the file of this patent UNITED STATES PATENTS 2,003,690 Lewton June 4, 1935 2,007,407 Sadtler July-9, 1935 2,114,281 Allen Apr. 19, 1938 2,839,065 Milton June 17, 1958 2,933,420 Haden Apr. 19, 1960 FOREIGN PATENTS 666,308 Great Britain Feb. 6, 1952 

1. A SMOKING PREPARATION COMPRISING SMOKING TOBACCO MIXED WITH A SMALL AMOUNT OF THE LAMINAR FORM OF "X"ALUMINA, SAID ALUMINA BEING FURTHER CHARACTERIZED BY HAVING AN ASTM BULK DENSITY OF ABOUT 2 LBS./CU. FT. 